Vehicle door latch assembly

ABSTRACT

A passenger vehicle door latch assembly ( 10 ) includes a cam e.g. ( 90   a ) rotating in common with a latching claw ( 30 ) which is retained by a pawl ( 34 ) at first safety and fully closed positions of an associated door, the shaping of the cam controlling operation of locking mechanism of the assembly. Lobes, e.g. ( 92   a,   92   b ) on the cam co-act to shift a release lever ( 64 ) of the mechanism back to an active position at which it will free the pawl by operation of a door handle for opening of the door even if it has previously been set to a disabled condition at which the door would otherwise be locked so as to prevent inadvertent slam locking of the door Different cams ( 90   a,    90   b,    90   c  or  90   d ) may be substituted in an otherwise common assembly to provide a selection of logic sequences of self-cancelling or prevention of locking operations.

This invention relates to latch assemblies for passenger vehicle doors.

More specifically it relates to rotating claw latch assemblies in whichthe assembly includes a pivoted claw having a mouth for receiving acoacting striker as the latter enters a recess of the assembly body onclosing the associated door. The claw is releasibly retained againstrotation which would allow the door to open by a resiliently loaded pawlengaging notches or ratchet teeth of the claw. The claw is so retainedat two angular positions or stages, a first safety position at which thedoor is not fully closed, and a fully latched position at which the dooris completely shut against its weather seals. The mechanism so definedis hereinafter referred to as “rotating claw mechanism”.

For most applications the assembly will also incorporate a lockingmechanism for the security of the vehicle with a view to preventingunauthorised access by in some way blocking or disabling the action ofthe door handles in releasing the pawl from engagement with the claw foropening the door.

Various forms or modes of operation of the locking mechanism arerequired to suit differing accepted practices in vehicle marketsthroughout the world, different customer requirements, and alsodifferent kinds of operation of the doors on an individual vehicle. Forexample there may be three different types of operation of the doors ofa four door passenger car, the two rear doors are not usually providedwith exterior key operated locks while the drivers and passenger frontdoors may have such locks but may each operate rather differently. Oneimportant consideration is prevention, so far as possible, of the keysbeing accidentally locked inside the car as would be the case if allfour doors had simple slam locking, ie all of them could be set to alocked condition while open which condition would remain undisturbed asthe doors were closed.

To avoid the latter problem at least one of the doors is usuallyprovided with a latch assembly incorporating locking mechanism havingsome kind of self-cancelling action whereby even if it is set to lockedcondition before closing the door it will be unlocked as the door closesor some kind of blocking action preventing the latch being set to lockedcondition while the door is open. These arrangements ensure that the keymust be used, or some conscious overriding operation effected, from theexterior to secure at least that door.

Various locking logic sequences are built into known locking mechanismsto meet different customer and market demands, for example:

a) Constant self-cancel i.e. the latch cannot be slam locked, closingthe door will always result in return to the unlocked conditionnecessitating use of the key or equivalent to secure the door.

b) Self cancel with keyless override i.e. simply swinging the door shutwill self-cancel any locking as above but with provision for overridingthat arrangement so that the door can be locked without use of the keyor like by a sequence of operations which is unlikely to be carried outinadvertently or by accident. This usually involves locking the latchmechanism prior to closing the door and then effecting closing whileholding the exterior door handle up or otherwise out of its position ofrest. This logic sequence is generally preferred in the Japanese market.

(c) Interacting i.e. instead of self-cancelling as (a) or (b) above itis impossible to set the locking mechanism into the locked conditionwhile the door is open, that is with the claw not in the first safety orfully latched positions.

(d) Interacting with keyless override i.e. the prevention of locking inthe open condition can be overridden by some conscious operation similarto (b) above, typically by holding the exterior handle up or otherwiseaway from its position of rest which bypasses the blocking of thelocking mechanism enabling the latter to be set to the locked conditionwith the door open. The handle can then be released enabling slamlocking with no self-cancelling and without need to use the key or thelike. This logic sequence is generally preferred in the European market.

(e) Various “hybrid” logic sequences, e.g. providing differences inoperation as between door fully open and door on first safetyconditions.

Each of these logic sequences has advantages and disadvantages. Thuswith keyless system (b) some users object to having to hold the doorhandle while pushing the door shut, it may require a two-hand operationand may involve contact with a wet or dirty vehicle exterior.

Some of these sequences, as provided in known vehicles, also havesecurity disadvantages. If the door is inadvertently left closed only tothe first safety position a self-cancelling or interacting sequence mayeither leave the latch mechanism unlocked without the user realisingthis, or may enable the mechanism to be shifted to the unlockedcondition due to the self-cancelling provision as by pushing the doorfurther closed to or towards the fully latched position so that it canthen be opened by an intruder.

U.S. Pat. No. 3,384,404 discloses a latch assembly having locking logicsequence of type (b) above i.e. self-cancel with keyless override. It isknown from this disclosure to provide said assembly with a pivotedcancellation member operating as a sensing formation adjacent to theclaw. A formation on the claw periphery engages said member if thelatter and associated locking mechanism has been set to locked conditionwhile the door is open to return it to unlocked condition as the clawrotates to angular positions corresponding to a safety and a fullylatched position of the door. The self-cancelling action of the sensingformation can be overridden by holding a manually operable element ofthe door in a shifted position while closing the door.

The object of the present invention is to provide improvements in latchassemblies having rotating claw mechanism, and more specifically in thelocking mechanisms thereof so as to provide economies of manufacture andassembly, and ease of adaptation of a standard assembly to a widevariety of locking logic sequences and forms of manual and/or poweroperation and control in a particularly simple manner and with minimuminventory of components. Further objects are improvements in vehiclesecurity and in durability and reliable operation of latch assemblies.

According to the invention there is provided a vehicle door latchassembly as distinguished in the claims.

An example of the invention is now more particularly described withreference to the accompanying drawings wherein:

FIG. 1 is elevation of a latch assembly with a back plate removed,

FIG. 2 exploded perspective view of said assembly,

FIGS. 3 to 9 are diagrammatic elevations of parts of latch and lockingmechanism of said assembly in various stages or conditions of operationand/or with various forms of cam installed for respective logicsequences.

Referring first to FIGS. 1 and 2, a latch assembly 10 comprises a strongpressed metal retention plate 12 (FIG.2) forming the outer face of theassembly when mounted on a vehicle door and having countersunk threadedapertures 14 to receive mounting screws. Plate 12 has two spacedparallel posts riveted thereto to extend from its inner face on eitherside of a slot 16 for entry of a doorpost striker 18. One of these postsis a claw post 20 and the other is a pawl post 22 each of which extendsthe full depth of the assembly.

A moulded plastics body 24 locates against plate 12 and has a body floor26 spaced from plate 12. A moulded plastics claw sleeve 28 is journalledon claw post 20 to extend through floor 26, the portion adjacent plate12 carrying a claw 30 of generally conventional form having a mouth 32to coact with striker 18. In this example the claw is of composite metaland plastics construction.

Pivoted on pawl post 22, again immediately adjacent to plate 12, is apawl 34 also of composite construction and resiliently urged by a pawlspring 36 into coacting relationship with first and second ratchet toothformations 38,40 on an arcuate edge part of claw 30 defining firstsafety and fully latched positions in known manner.

Pawl 34 carries a pawl stop pin 42 spaced from post 22 which projectsthrough an arcuate slot in body floor 26.

A claw spring 44 located in an arcuate groove of body 24 urges claw 30anti-clockwise as viewed in the drawings, i.e. towards the door releaseposition so that the door is freed for opening when pawl 34 is shiftedout of engagement with the claw.

The actuating and locking mechanism of the assembly is located generallywithin body 24 on the side of floor 26 remote from plate 12, ieuppermost as viewed in the drawings.

The version of the assembly now described will typically be used atleast on the driver's door of the vehicle having inside and outside doorhandles for unlatching the door when closed, an inside sill button orequivalent manual locking actuator for locking and unlocking the closeddoor from inside the vehicle, and an exterior key barrel for manuallocking and unlocking using appropriate key.

A handle lever 60 is fulcrummed for angular movement on the distal endof claw post 20 overlying claw sleeve 28 and extends transversely ofbody 24, its left-hand arm as seen in the drawings being operativelylinked to the exterior door handle. A return spring 62 acts on the otherarm to bias lever 60 clockwise as seen in the drawings.

A release lever 64 is pivoted at one end to an intermediate part of saidlefthand arm to extend generally normally of lever 60 towards the pawlstop pin 42. The end of lever 64 adjacent said pin is bent towards floor26 forming an abutment to engage that pin on movement of lever 60 fromits position of rest, so effecting release of claw 30 to unlatch thedoor if release lever 64 is angularly positioned in alignment with pin42.

A moulded plastics lock lever 66 is journalled for angular movement onthe distal part of pawl post 22. One arm of this lever extends generallytowards release lever 64 and it is pivotally coupled thereto by alocking clutch link 68 so that angular movement of lock lever 66 swingsrelease lever 64 into and out of alignment with pawl stop pin 42. Whenlever 66 is turned clockwise it draws release lever 64 to the right asseen in the drawings putting the mechanism in the locked condition inwhich release lever 64 is disabled, it will still move in conjunctionwith handle lever 60 but cannot abut stop pin 42 to unlatch claw 30.Lock lever 66 will be operatively linked to the interior sill button orequivalent. A torsion type index spring 70 acts between lock lever 66and body 24 to assist in indexing lever 66 to its respective limitpositions at each end of its travel.

A moulded post 77 upstanding from floor 26 spaced from pawl post 22pivots a key lever 78 having an outwardly projecting arm which will beoperatively linked to the exterior key barrel. The inward arm portion ofthat lever is in the form of a fork co-acting with a projectingformation of lock lever 66 for shifting it between locked and unlockedpositions by the use of the key.

The last described mechanism is retained in place and substantiallyenclosed by a pressed metal back plate 80 (Fig.2) secured by rivetingthe ends of posts 20 and 22. Plate 80 includes a projecting trunnion 82on which is pivoted an inside handle lever 84, one of arm of whichcoacts with an abutment at the end of the right hand arm of handle lever60 for actuation of the latter from the inside door handle in use.

In the form thus far described latch assembly 10 does not incorporateany self-cancelling or other locking logic sequence, the lockingmechanism can be set in the locked condition with the door open, closedor at first safety and slam locking is therefore always possible i.e.lock lever 66 can be shifted to the locked position as by use of thesill button with the door open and the door can then be slammed shut (ormay swing shut inadvertently) without disturbing that setting and withthe possibility, if the other doors are already locked, that the keysmay be locked inside the vehicle.

It will be understood that this arrangement may be acceptable for someapplications e.g, the lock assemblies for rear passenger doors (whichare often not provided with external key barrels so that locking can beeffected by use of the sill buttons only, in which case key lever 78will be omitted from the assembly) or, in combination with externallocking by key barrel, for the front passenger door of the vehicle.

It is usually desired that at least one door, typically the driver'sdoor, has some form of self-cancelling or inter-acting locking logic andthis will now be described utilising the standardised latch assembly 10with the simple addition or interchange of a single component.

That part of claw sleeve 28 which projects beyond body floor 26 isshaped for driving engagement with a press-fit claw angle sensing cam 90which can take various forms a first of which, 90 a, is shown in FIGS. 1to 6 of the drawings.

The operation thereof is best illustrated in FIGS. 3 to 6, said camhaving two angularly separated radial projections or lobes 92 a, 92 b.The floating locking clutch link 68 includes a shaped projection 94extending generally in the direction of the claw post 20 with handlelever 60 at its position of rest (FIGS. 1 and 3) and, when link 68 iscarried to the right and shifted nearer post 20 (FIGS. 4 and 5)projection 94 is brought closest to the post axis in which position itintersects the path of movement of cam lobes 92 a, b.

This arrangement provides self-cancelling locking logic with facilityfor keyless override. If the mechanism is set to locked condition, as bythe sill button, with the door open, ie with claw 30 at its unlatchedposition both lobes 92 a, 92 b will be angled to the right of projection94 which lies in their path (FIG. 4). If the door is now closed to thefirst safety position the leading lobe 92 b will kick link 68 to theleft and downwards shifting release lever 64 into alignment with pawlstop 42 i.e. the latch is set back to unlocked condition.

If locking is effected at this first safety position projection 94 willenter between lobes 92 a and 92 b (FIG. 5) and pushing the door fullyshut will again shift the mechanism to unlocked condition by co-actionof trailing lobe 92 a with projection 94.

The door can be locked from the outside without use of the key ifdesired by setting to locked condition using the sill button and holdingthe outside door handle to keep handle lever 60 rotated anti-clockwise(FIG. 6). This holds clutch link 68 back to underlie release lever 64even though the latter is at its unlocked position, keeping projection94 clear of the cam lobes 92 so that there is no self-cancellinginteraction with the latter and slam locking can be effected i.e. thislogic sequence provides self-cancel with keyless override.

Another form of cam 90 b is shown as substituted in the FIG. 7arrangement. This cam has a single continuous lobe 95 with an angularextent of some 80°, extending in the anti-clockwise directionsubstantially beyond the angular compass of the above two lobes 92 a, 92b. This form of cam prevents the mechanism being set to the lockedcondition at any angular position of claw 30 other than the fullylatched position with the door completely shut, so providing theinteracting type of locking logic sequence preferred for the Europeanmarket; locking cannot be effected at the first safety position.

Again a keyless overriding operation is allowed, putting the handlelever 60 to the position shown in FIG. 6 and setting the lockingmechanism to locked condition will bypass or override the interacting orblocking action afforded by cam 90 b.

Yet another form of cam 90 c is shown in FIG. 8 (15) having a singlelobe 96 of lesser angular extent than lobe 95, in this example about50°. This allows the mechanism to be set locked whatever the door handleposition when the door is open but self-cancels such locking immediatelythe claw moves to or beyond the first safety without permittingresetting to locked position at first safety.

A further form of cam 90 d is shown in FIG. 9 (16) having only a singlenarrow lobe 98 equivalent to lobe 92 a of cam 90 a but omitting lobe 92b. This will self-cancel when the claw shifts from open to first safetypositions but, if locking is effected at the latter position, there willbe no self-cancel if the door is then pushed fully shut.

The sensing of latch condition directly from the claw by means of theinterchangeable cams simplifies the construction and assembly andrequires a minimum of components to provide a wide range of types ofoperation and logic sequences. Previously attempts have been made toprovide sensing for logic sequences by reading pawl movement but this isunsatisfactory because the pawl moves twice over the same path inengaging the claw at first safety and fully latched positions so that itis difficult to differentiate between said positions. Specialadaptations such as making the two claw ratchet teeth different depthsso that the pawl travels over different distances are unsatisfactorybecause they may affect the security of the door latching, give anunsatisfactory “feel” during operation; and/or add to the complexity ofthe mechanism and render it less adaptable.

While purely mechanical and manual direct operation has been describedabove it will be understood that latch assemblies of the invention canreadily be provided with electric servo-actuators for operation as partof a central locking system or other remotely controlled system e.g. forlocking all doors in unison. Instead of an external key-barrel therelevant door or doors may be provided with electrical sensors forresponse to coded signals from an infra-red or other non-mechanical keydevice. The assembly may include sensor switches 100, 102 (FIG. 2) forsignaling the condition of the related latch and locking mechanism to acentral control unit or other remote station, in the example switch 100is a “door ajar” switch and switch 102 is a “door locked” switch.

What is claimed is:
 1. A latch assembly (10) for a passenger vehicledoor including: a) a pivoted claw (30) having ratchet formations (38,40)and a mouth (32) for operatively receiving a coacting striker (18) asthe latter enters a recess of the assembly body (24) on closing theassociated door; b) a resiliently loaded pawl (34) engaging the ratchetformations of the claw to releasably retain the latter against rotationwhich would allow the door to open at either of two angular positions, asafety position at which the door is not fully closed, and a fullylatched position at which the door is fully closed; c) a lockingmechanism for preventing unauthorised access by way of the door in useacting to block or disable the action of an element or elements (60,84)worked by a handle or handles of the door in releasing the pawl fromengagement with the claw for opening the door; d) means for operativelysensing different conditions of the claw and pawl combination respectiveto the door being open, at the safety position, or fully latched, orbetween at least any two of those conditions, in response to theoperative angular position of the claw; and e) a purely mechanical logicsequence means operating to control the action of the locking mechanismin response to the displacement of said ratchet formations;characterized in that said means for sensing includes a sensing camformation (90) operatively co-acting with an element (68) of the lockingmechanism to control the action of the latter in a logic sequencedictated by the cam profile, action of the element effecting mechanicalaction of the locking mechanism, said sensing cam formation beingoperatively mounted co-axially with the claw and coupled for rotationtherewith so as to be positively angularly indexed by angular movementof the claw (30) for sensing said conditions.
 2. An assembly as in claim1 characterised in that the locking mechanism includes a release element(64) operatively coupled to the element (60) worked by a movable handleof the door and selectively displaceable by the action of locking meansbetween an active position at which movement of the handle causes therelease element to displace the pawl (34) from engagement with the claw(30) to free the door in use and a disabled position at which movementof the handle element is not communicated to the pawl.
 3. An assembly asin claim 2 characterised in that the sensing formation (90) controls theaction of the locking mechanism by coacting with the release element(64).
 4. An assembly as in claim 3 characterised in that the camformation (90 a) has two angularly separated radial projections (92 a,b)each of which acts to return the release element (64) to the activeposition from previous setting to the disabled position upon rotation ofthe claw (30) in door closing direction to the first safety position andfrom the latter position to the fully latched position respectively. 5.An assembly as in claim 3 characterised in that the cam formation (90 b)has a radial projection (95) of sufficient angular extent to maintainthe release element (64) at the active position at any angular positionof the claw (30) other than the fully latched position.
 6. An assemblyas in claim 3 characterised in that the cam formation (90 c) has aradial projection (96) of sufficient angular extent to maintain therelease element (64) at the active position throughout rotation of theclaw (30) in door closing direction from and including the first safetyposition and up to but not including the fully latched position.
 7. Anassembly as in claim 3 characterised in that the cam formation (90 d)has a single radial projection (98) acting to return the release elementto the active position from previous setting to the disabled positionupon rotation of the claw in door closing direction to the first safetyposition without restricting setting of the release element to thedisabled position at or past the first safety position.
 8. A latchassembly for a passenger vehicle door comprising: a) a pivoted clawhaving ratchet formations and a mouth for operatively receiving acoacting striker as the latter enters a recess of an assembly body onclosing of the associated passenger vehicle door; b) a resilientlyloaded pawl engaging the ratchet formations of the claw to releasablyretain the latter against rotation which would allow the door to open ateither of two angular positions, a safety position at which the door isnot fully closed, and a fully latched position at which the door isfully closed; c) a locking mechanism to block or disable the action ofat least one element worked by at last one handle of the door inreleasing the pawl from engagement with the claw for preventingunauthorized access by way of the door; d) a sensor for operativelysensing different conditions of the claw and pawl combination respectiveto the door being open, at the safety position, or fully latched, orbetween at least any two of those conditions, in response to theoperative angular position of the claw; and e) a purely mechanical logicsequence controller to control the action of the locking mechanism inresponse to the displacement of said ratchet formations.
 9. The assemblyof claim 8 wherein said sensor includes a sensing cam formationoperatively co-acting with an element of the locking mechanism tocontrol the action of the latter in a logic sequence dictated by the camprofile, action of the element effecting mechanical action of thelocking mechanism, said cam formation being operatively mountedco-axially with the claw and coupled for rotation therewith so as to bepositively angularly indexed by angular movement of the claw for sensingsaid conditions.
 10. The assembly of claim 8 wherein the lockingmechanism includes a release element operatively coupled to an elementworked by a movable handle of the door and selectively displaceable bythe action of locking means between an active position at which movementof the handle causes the release element to displace the pawl fromengagement with the claw to free the door in use and a disable positionat which movement of the handle element is not communicated to the pawl.11. The assembly of claim 8 wherein the sensor controls the action ofthe locking mechanism by coacting with the release element.
 12. Theassembly of claim 8 wherein the cam formation has two angularlyseparated radial projections, each projection acts to return the releaseelement to the active position from a previous setting to the disabledposition upon rotation of the claw in door closing direction to thefirst safety position and from the latter position to the fully latchedposition respectively.
 13. The assembly of claim 8 wherein the camformation has a radial projection of sufficient angular extent tomaintain the release element at the active position at any angularposition of the claw other than the fully latched position.
 14. Theassembly of claim 8 wherein the cam formation has a radial projection ofsufficient angular extent to maintain the release element at the activeposition throughout rotation of the claw in door closing direction fromand including the first safety position and up to but not including thefully latched position.
 15. The assembly of claim 8 wherein the camformation has a single radial projection acting to return the releaseelement to the active position from previous setting to the disabledposition upon rotation of the claw in door closing direction to thefirst safety position without restricting setting of the release elementto the disabled position at or past the first safety position.
 16. Alatch assembly (10) for a passenger vehicle door including: a pivotedclaw (30) having a mouth (32) for operatively receiving a coactingstriker (18) as the latter enters a recess of the assembly body (24) onclosing the associated door, a resiliently loaded pawl (34) engagingnotches or ratchet teeth (38,40) of the claw to releasably retain thelatter against rotation which would allow the door to open at either oftwo angular positions, a safety position at which the door is not fullyclosed, and a fully latched position at which the door is fully closed;and a locking mechanism for preventing unauthorized access by way of thedoor in use acting to block or disable the action of an element orelements (60,84) worked by a handle or handles of the door in releasingthe pawl from engagement with the claw for opening the door:characterized in that the assembly further includes means foroperatively sensing or distinguishing between different conditions ofthe claw and pawl combination respective to the door being open, atfirst safety, or fully latched, or between at least any two of thoseconditions, said means including a sensing formation (90) displaced byrotation of the claw so that said sensing or distinguishing is effectedin response to the operative angular position of the claw; and a purelymechanical logic sequence means operating to control the action of thelocking mechanism in response to the displacement of said formation, inwhich formation (90 d) acts to return the release element to the activeposition from previous setting to the disabled position upon rotation ofthe claw in door closing direction to the first safety position withoutrestricting setting of the release element to the disabled position ator past the first safety position.
 17. The latch assembly of claim 1wherein the means for operatively sensing different conditions of theclaw and pawl combination is mechanical.
 18. The latch assembly of claim8 wherein the sensor for operatively sensing different conditions of theclaw and pawl combination is mechanical.
 19. The latch assembly of claim16 wherein the means for operatively sensing or distinguishing betweendifferent conditions of the claw and pawl is mechanical.